The purpose of the National HIV Behavioral Surveillance program is to monitor the HIV epidemic through HIV behavioral surveillance. The objectives of this program are to maintain an ongoing surveillance system to ascertain the prevalence of HIV risk behaviors and HIV infection among groups at high risk for acquiring HIV infection to use in developing and directing both local and national prevention services and programs. Data collection will rotate each year among men who have sex with men (MSM), injecting drug users (IDU), and heterosexuals at increased risk for HIV infection. NHBS is an anonymous, cross-sectional, multisite survey that utilizes a standardized questionnaire. Sampling and recruitment strategies will include venue based, time-space sampling and respondent driven sampling surveys. A minimum of 500 eligible participants each year/risk group will be enrolled. This system will assess risk behaviors and access to and utilization of HIV prevention programs. Voluntary testing for HIV infection will be conducted in order to assess HIV seroprevalence and incidence. In addition, hepatitis testing will be offered during all cycle in order to measure the prevalence in high-risk populations. Transgender HIV Behavioral Surveillance (THBS) will also be implemented to strengthen the national capacity to monitor the HIV epidemic and improve the direction and evaluation of prevention efforts among male-to-female transgender persons. The THBS data will also serve to meet the CDC HIV Prevention Strategic Plan objective of improving surveillance of HIV-related risk behaviors among transgender or gender variant persons. This program will provide an opportunity to capitalize on experience recruiting at-risk individuals from non-health care community settings using scientifically sound methodologies to maintain an ongoing system for surveillance of behaviors related to HIV acquisition. This will strengthen the capacity nationwide to monitor the HIV/AIDS epidemic, develop and implement effective HIV prevention interventions and evaluate prevention programs.